The invention concerns an apparatus for the optimization of the regulation adjustment of a spinning preparation machine with, for example, a draw frame, in particular, a regulated draw frame, a carding machine, or a combing machine. Likewise, the invention concerns first a procedure corresponding to a regulation of said machines and second, a machine for a spinning works.
A spinning preparation machine with a regulated draw frame can be, for example, the regulated draw frame RS-D 30 of the Firm Rieter, wherein the thickness-variations of the entering fiber bands at the feed end are continually monitored by a mechanical device (groove-roll/feeler roll) and subsequently converted into electrical signals. The measured values are transmitted to an electronic memory with a variable, time delayed response. The time delay allows the draft between the mid-roll and the delivery roll of the draw frame to occur exactly at that moment when the band piece, which had been measured by a feeler roll pair, finds itself at a point of draft. The time delay then reacts so that corresponding band pieces can run through the distance between the feeler roll pair and the first location of draft. When the piece of band reaches the hypothetical draft point in the draft field, a corresponding value is released by the electronic memory. The distance, which separates the feeler roll pair and the point of draft, respectively, is called the zero point of regulation. When the zero point is reached, then, conditioned by the value of the measurement, a variable speed motor positioning operation is carried out.
Especially in the case of a change of fiber material, or batches thereof, in regulated draw frames and generally in the case of all spinning machines and universally where textile machines are concerned, extensive re-optimization of the machine regulation is necessary. In the case of draw frames, for instance, the mechanical adjustments must be optimized. These mechanical adjustments include the lengths of the draft fields, the tensioning, the upper roll loadings, the speed of output and the like.
At the same time, the process controlling parameters must be adjusted anew. This adjustment would include the zero point, the intensity of the regulation, (i.e., the amplification of the variable speed motor control), the setting of band fineness, that is, the length related thickness of the band, and the correction values in the case of a slow run of the machine. Actually, sensors measure the band thickness. As a matter of common speech usage, “band fineness” and “band thickness” are employed as synonyms.
A possibility for the determination of at least the optimal regulation intensity is made available by the so-called “bands-test”. With this testing, it is expected that inherent machine behavior and material-specific idiosyncrasies would be reliably detected independently of the regulation. The bands-test is carried out in a random sampling manner and executed manually for the determination of the correct control of thickness variation of the fiber band(s). In conducting this testing, first, the normal number of fiber bands present (for instance, six bands) which are being drawn is determined, and at the same time the variations thereof are controlled. Thereafter, one of the bands present is removed, and the remaining bands are subjected to control, so that the required thickness of a band when the normal number of bands are present is achieved. In a converse example, an additional band can be added to the original number of the present fiber bands (in the example, the named 6 bands). The bands are again so controlled, that the band thickness appropriate to the original band number is obtained. From each three steps, samples of a specified length, for instance, of 25 m, are taken out and weighed. (In the speech of the practice, the expression “ktex” is used for the term “band-weight”.) This procedural method is repeated a number of times to achieve a statistically secured value. Deviations of the A %-value (A %=percent-based, band thickness deviation) of the drawn, controlled band are determined from the obtained mean values, which represent a three-point measurement. The described bands-test is repeated, until an acceptable A %-deviation (for example, <0.1%) is attained. The procedure and the basis for the calculations as carried out for the draw frame RSB-D 30 of the Firm Rieter are described, for example, in the brief operational manual under Item 2.31, Section 3C/100 to 3C-102.
The bands-test described requires a large investment in time and materials. In the case of the exchange of small batches, such an investment is unwarranted. An additional problem is, that where critical fiber materials are involved, the testing conditions must be held within very exact limits. For example, under certain circumstances of humidity in the working space, fiber material picks up moisture in different quantities, which can falsify the comparativity of the test values. In DE 42 15 682, teaches a method of conducting an automatic bands-test, wherein a transient signal regarding a thickness portion can be directed to an on-line execution of a bands-test. This procedure has, however, the disadvantage, that the regulation fluctuates permanently so that the regulating parameters, especially the regulation zero point and the intensity of regulation, become biased because of the measurements at the output end of the draw frame. In this way, both an interrupted and therefore a not necessarily desired regulation behavior follows which can bring about a chaotic control situation. In an alternative variant of the DE 42 15 682, the transient signal is generated via a reserve band which is infed temporarily, which adds to causing this procedure to also be complex and time consuming.
A further complicated adaption of the parameters for regulation is necessary if the values of the band weight sensors or band thickness sensors at the draw frame feed end, during a specified slow run of the machine (as compared to normal speed, i.e., 800 to 1000 ma/min) must be corrected dependent on the characteristics of the fiber material. In accord with the previously described mechanical feeler-roll system at the entry to the draw frame, it became evident that the feeler roll measurement differs as the speed varies.
Further, the penetrating depth of the feeler roll is dependent upon the kind of fiber, even when thickness does not change. On this very account, previously, with the mentioned Rieter machine, for example, the cited “Adaption to Fiber Type” process is carried out.
Reference can be made, for example, to the brief operational manual for the above mentioned draw frame RSB-D 30 of the firm Rieter under Item 2.30, Section 3C/99. In this reference it is found that the actual band-thickness at the draw frame output end (that is, delivered band thickness) with a slow running machine can be compared with the same delivered band thickness, but processed at a normally fast delivery speed. As part of this comparison, the effect on the band exiting from the draw frame because of weight differentiation was examined. This examination included producing a band sample of, for example, 10 m long at normal operating speed and subsequently, producing the same during a slow run, the latter being perhaps one-sixth of the normal speed. From the result of the weight comparison of the samples, the operating person, having the predetermined standard values (“x % difference between the two actual band-thicknesses somewhat corresponding to a change as referred to in “Adaption to Fiber Type” of y %), can input on an operation panel the correction for measurement error in the values for the slow run of the machine. This procedure is also time consuming, restricts production and is costly.